The strongest evidence for this is that NATO even exists at all in 2023.
After V-E day we had a formidable occupation army in place. We didn’t need a NATO if we had wanted to stay there. Instead, we had a mad scramble of demobilization and wholesale repatriation of troops, also redeployment of troops to the Pacific. Even then we still had a large contingent in Western Europe. Paul Johnson’s Modern Times goes into it in detail. NATO was organized at the urgent behest of the western allies.
As someone who was assigned to a NATO command in Italy 1968-70, I can assure you that the 500,000 American military personnel (excluding dependents) stationed in Europe were there to defend against an attack by the Soviets. The big concern was that they would come through the Fulda Gap. The Soviets had a large, well-trained military force, a legacy from WWII. The 1960s were tumultuous times with the erection of the Berlin Wall, the Cuban Missile Crisis, and the Prague Spring. And then there was Vietnam and the civil rights movement.
At that time West Germany had a robust, highly capable military presence.
The Soviet request to join NATO in 1954 was turned down because ‘the unrealistic nature of the proposal does not warrant discussion’. If you recall, the Soviets blocked all land access to Berlin from June 1948 until May 1949. The Berlin airlift kept the Allied sectors of Berlin alive and functioning. NATO was founded in April 1949. The Berlin Airlift was still ongoing.
Churchill made his Iron Curtain speech on March 5, 1946 that articulated the threat that the Soviet Union and communism posed to peace and stability in the post war world. It would be ludicrous to think that the Soviets were serious about joining NATO or that NATO would even consider it.
In August 1949 the Soviets had their first successful test of an atomic bomb. From then on, they conducted numerous tests and built a formidable atomic weapons arsenal. This certainly changed the global balance of power. And the thought of Stalin with nuclear weapons was disconcerting to the West to say the least.